The next episode of the comedy series "The Big Bang Theory" season 11 will feature something that will catch Sheldon Cooper's (Jim Parsons) attention. It will also reveal a secret from that past that may affect the relationship of Penny (Kaley Cuoco) and Leonard Hofstadter (Johnny Galecki).

The latest episode was about Sheldon keeping a secret from Leonard and Howard (Simon Helberg) when he worked with the U.S. Air Force. Sheldon could not understand why they were angry and proceeded with the project.

However, Leonard and Howard wanted to take revenge by working with Barry Kripke (John Ross Bowie) to make an improved version of Sheldon's technology. Everyone was surprised when the Air Force said that they no longer needed Sheldon's project. Later on, they found out that Barry sold the technology without letting Leonard and Howard know.

Meanwhile, the next episode will feature another conflict between Sheldon and the guys. According to the synopsis of "The Big Bang Theory" season 11 episode 9, titled "The Bitcoin Entanglement," Sheldon will try to teach the guys a lesson because of their move to exclude him from the Bitcoin investment.

On the other hand, Leonard will have some flashbacks, and he will try to remember the things that occurred seven years ago. He will recall a valuable investment, thinking that it will bring him a lucrative amount of money. Aside from that, Leonard and Penny will face something that might threaten their relationship.

Penny's old friend Zack (Brian Thomas Smith) will arrive to show them an old video. The clip will fascinate Zack, but not Penny. She will be uneasy because the clip will reveal something from her past with Leonard, a memory that Penny wants to forget.

Episode 9 of "The Big Bang Theory" season 11 will air on Thursday, Nov. 30, at 9 p.m. EST on CBS.